Opening/closing device, molding apparatus, and molding method

Abstract

An opening/closing device (14) includes: a stationary platen (20); a movable platen (22) capable of moving toward or away from the stationary platen (20); an opening/closing mechanism (28) having a plurality of toggle links (30, 31, 32) at least one (32) of which is connected to the movable platen (22); a driving device (37) including a cross head (26) connected to at least one (30) of the toggle links and capable of moving the movable platen (22); and a control portion (50). The control portion (50) is configured to control the cross head (26) such that the movable platen (22) moves at fixed speed during fine die-opening operation.

The invention claimed is: 
     
       1. An opening/closing device comprising:
 a stationary platen; 
 a movable platen capable of moving toward or away from the stationary platen; 
 an opening/closing mechanism having a plurality of toggle links at least one of which is connected to the movable platen; 
 a driving device including a cross head connected to at least one of the toggle links and capable of moving the movable platen; and 
 a control portion configured to control the cross head such that the movable platen moves at a fixed speed during fine die-opening operation, 
 wherein a cross head movement distance through which the cross head moves at the time of fine die-opening operation is divided into a plurality of sections, with a speed of the cross head being determined beforehand for each of the plurality of the sections such that the moveable platen moves at a fixed speed during the fine die-opening operation, 
 at the time of the fine die-opening operation, the control portion moves the cross head at the speed determined beforehand for each section, and 
 in the plurality of sections, a first range of die closing side position along the cross head movement distance includes a first set of successive sections, each of which has the same first length, and a second range of die opening side position along the cross head movement distance includes a second set of successive sections, each of which has the same second length, the first length being shorter than the second length. 
 
     
     
       2. A molding apparatus comprising an opening/closing device according to  claim 1 . 
     
     
       3. A molding method employing an opening/closing device according to  claim 1 , and comprising a step in which, at the time of fine die-opening operation, the cross head is moved such that the movable platen moves at a fixed speed. 
     
     
       4. The opening/closing device of  claim 1 , wherein each speed of the cross head is determined beforehand for each of the plurality of sections to be different from each other successively such that the movable platen moves at the fixed speed during the fine die-opening operation. 
     
     
       5. The opening/closing device of  claim 4 , wherein each respective speed of the cross head is determined to be fixed beforehand for each of the plurality of sections through which the cross head moves at the time of the fine die-opening operation. 
     
     
       6. The opening/closing device of  claim 1 , wherein the cross head movement distance through which the cross head moves at the time of fine die-opening operation includes the first range of the die closing side position and the second range of the die opening side position along the cross head movement distance. 
     
     
       7. The opening/closing device of  claim 6 , wherein the first range from the die closing side position ranges from 0 to 50 mm and is divided into 50 sections each of 1 mm long. 
     
     
       8. The opening/closing device of  claim 6 , wherein the second range from the die closing side position ranges from 50 to 150 mm and is divided into 50 sections each of 2 mm long, and wherein the speed of the cross head is gradually reduced during the second range.